Seed regeneration is necessary when germination rates fall below 85% or seed quantity decreases. Regeneration ensures adequate seed stocks for distribution and conservation. A regeneration plan identifies which accessions need regeneration based on viability and availability. For sorghum accession regeneration, seeds are planted in well-managed field plots at a density of 50+ plants per accession. Seed is harvested once mature, processed, tested, and stored to maintain genetic integrity. Thorough documentation tracks regeneration activities and results.

2. Seed Regeneration
Content:
 What is regeneration
 When is regeneration necessary
 How to plan regeneration

3. 1. What is Regeneration?
• Regeneration is the renewal of germplasm accessions by sowing seeds or
planting vegetative materials and harvesting which will posses the same
characteristics as the original population
• Seeds in storage lose viability or become depleted in quantity over time
• Thus, Regeneration of conserved accessions in storage is made when the seed
quality(germination) or the seed quantity, or both, fall below a certain critical
level.
• Critical level = Germination percentage below 85% of the initial value
= Available seed packets become 2 and less

4. 2. Why is Regeneration Necessary?
• Initial seed increase or multiplication(new collections or materials
received by donation insufficient)
• Long-term conservation (accessions that are not yet in the base
collection)
• Replenish seed stocks in active and base collections
• Seed regeneration should be done for accessions that have:
 Low viability identified during periodical monitoring (regeneration)
 Insufficient stocks for either distribution or conservation (multiplication)
Fresh and/or Enough seed is available for users

5. Procedures for regeneration
1. Selection of accessions, using the passport data
2. Preparation of regeneration plots
3. Sowing and crop management

6. 4. Determining and using appropriate pollination control for out
breeders
oPollination can be cross pollination or self pollination.
o it is important to properly control cross-pollination by wind and
insects by using cluster bagging
 for maintain the genetic integrity of individual accessions.
5

7. Con….
5 Harvesting and postharvest management
6. Verifying accession identity
7. Seed processing and drying

8. 8. Initial viability testing
9.Packaging and storage

9. 3. Regeneration plan
• How many accessions to regenerate annually? (available resource)
• Which accessions and species has an urgent needs?
• What is the last viability percentage of the accession?
 Regeneration sites of the crops

10. Regeneration of sorghum
• Sorghum (Sorghum bicolor (L.) Moench.) belongs to the Poaceae
family .
• It is considered to be one of the most important cereal crops in the
world
When to regenerate
• When germination falls below 85%.
• Available seed packets become 2 and less

11. Cont…….
Seed sample
• Sorghum is seed propagated. To maintain genetic integrity, use seed
from the original source as far as possible.
• At least 50 plants are required for regeneration, preferably more.
• About 8–15 g of seed (depending on seed size) are required for
regenerating an accession.
• For each accession, prepare one seed packet for planting each row.
• Label the packets with identification number and row number and
arrange them according to field lay-out.

12. Cont……
Field selection and preparation
• Select fields in which sorghum was not grown in the previous year.
• Choose a field with good drainage that is weed-free at the time of
sowing to ensure a good reserve of soil moisture.
• Prepare the land to a fine tilth by deep ploughing,.
• Level the field and make ridges 75 cm apart. This facilitates better
establishment of seedlings and plant stands.

13. Planting layout, density and distance
• Divide the field into plots (also known as tiers), leaving 1-m walking space
between them. The plots can vary from 3 to 9 m wide depending on the
size of the field.
• Mark rows 75 cm apart across each tier, perpendicular to the length of the
field, giving rows of 3–9 m long, depending on the width of the plot.
• Ensure a minimum distance of 3 m between different accessions.
Planting method
• Assign row numbers in a serpentine pattern (i.e. planting from left to right
in the first row followed by right to left in the second row or vice versa).
• Sow mechanically by using hand

14. Cont………
Labelling
• Label each accession with a tag fastened to a stake about knee height.
• Use strong paper for tags to withstand weathering.
Crop management
• Cover the panicles in well labelled paper bags
• Remove bags after 21 days
Fertilization
• Apply fertilizers (nitrogen and phosphorus, each at 40 kg/ha.
• As a second dose, apply nitrogen at the rate of 40–60 kg/ha between rows
30 days after planting.

15. Weed management
• The crop was kept free from weeds
Harvesting
• Identify seed maturity by the formation of a black layer on the seeds.
• Harvest and thresh seed manually.
• Cut the panicles and Collect panicles from each plot in a well-labelled
bag (label both inside and out with accession and plot numbers).

16. Cont…..
Post-harvest management
• Dry panicles in shade for a week until seed moisture content are reduced to 12% (ideal
for hand threshing).
• Thresh individual panicles by beating gently and clean the seeds.
• Verify accession identity using seed traits
• Send a representative sample for observations on seed traits,
• Collect the seeds in a labelled muslin cloth bag for further drying,
• preferably at a lower temperature and relative humidity (20–25°C and about 30–40%
relative humidity).
• Keep seeds at these conditions until seed moisture is 8–9% (for medium-term
conservation).
• For long-term conservation, dry the seeds to 5–7% moisture content.
• Seed health and viability testing.
• Pack seeds in moisture-impermeable containers (aluminium foil) for conservation and
distribution.

17. Cont…..
Documentation of information during regeneration
• Regeneration site name and map/GPS reference
• Name of collaborator
• Field/plot/nursery/greenhouse reference
• Accession number; population identification
• Source of seed
• Generation or previous multiplication or regeneration (if generation is not
known)
• Preparation of planting materials (pre-treatments)
• Sowing date and density
• Field layout used

18. Cont…..
• Field management details (watering, fertilizer, weeding, pest and disease control,
stresses recorded, others)
• Environmental conditions (altitude, precipitation, soil type, others)
• Emergence in the field or greenhouse (number of plants germinated)
• Days from sowing to flowering
• Pollination control method used (method, number of plants pollinated)
• Harvest date and method
• Number of plants harvested
• Quantity of seeds harvested
• Agronomic evaluation; agro-morphological traits recorded
• Comparisons with reference materials (record any identification numbers or references
of any samples taken from this regeneration plot)
• Post-harvest (describe any relevant procedures)

19. Thank you